Expressions

An expression is syntactic construct which can be evaluated into a value.

Expr ::=
  | Name                Variable reference
  | Path (:: TypeArgs)  Item reference
  | Value               Value literal
  | Query               Queries
  | _                   Placeholder
  | new Name (: Expr)?             Variant-construction
  | { ExprRecordField,* (| Expr)? }  Record-construction
  | dyn { ExprRecordField,* (| Expr)? }  Dynamically-typed record
  | [ Expr,* (| Expr)? ]           Array-construction
  | Expr? .. (=? Expr)?            Range-construction
  | fun Params (: Type)? = Expr    Lambda-function construction
  | Expr BinOp Expr   Binary operation
  | Expr UnOp         Unary operator
  | Expr ( Expr,* )   Function call
  | Expr . Name       Field projection
  | Expr . [0-9]+     Index projection
  | Expr . { Name,+ } Fields projection
  | Expr . ( ([0-9]+),+ ) Indexes projection
  | Expr : Type      Type annotated
  | if Expr Block (else Block)?            If-else-expression
  | match Expr Arms                        Match-expression
  | for Pattern in Expr Block              For-loop
  | while Expr Block                       While-loop
  | loop Block                             Infinite loop
  | break Expr? | continue | return Expr?  Jumps
  | try Expr catch Arms (finally Expr)?    Exceptions

UnOp ::=
  | -    Arithmetic negation
  | not  Logical negation

BinOp ::=
  | +   | -  | *   | /    | **  | %     Arithmetic
  | ==  | != | <   | >    | <=  | >=    Equality and comparison
  | and | or | xor | band | bor | bxor  Logical and bitwise
  | in  | not in                              Contains

ExprRecordField ::=
  | Name : Expr
  | Expr
  | Expr . Name

Operators

Operators are defined as follows, with precedence from highest to lowest:

(*) Operand is optional.

Builtin Functions

The builtin functions of Arc-Lang are listed here.

Examples

Basic function calls

{{#include ../../../arc-lang/examples/basic.arc:example}}

Lambda functions

{{#include ../../../arc-lang/examples/lambda.arc:example}}

Binary operators

{{#include ../../../arc-lang/examples/binops.arc:example}}

Placeholders

An expression-argument such as _ + _ desugars into a lambda function fun(x0, x1): x0 + x1

{{#include ../../../arc-lang/examples/placeholder.arc:example}}

Binary operator lifting

Binary operators can be lifted into functions.

{{#include ../../../arc-lang/examples/binopref.arc:example}}

String interpolation

String interpolation is supported using the $ and ${} syntax.

{{#include ../../../arc-lang/examples/interpolate.arc:example}}

Query

{{#include ../../../arc-lang/examples/query.arc:implicit}}